Multiple spark printer



Dec. 31, 19 8 s. SCHMIDT 3,419,752

IULTIPLE SPARK PRINTER Filed Sept. 10, 1965 Sheet of s INVENTOR. v

' SIEGERIE'D SCHMIDT BY M (I AGENT Sheet 2 of 5 S. SCHMIDT MULTIPLESPARK PRINTER Dec. 31, 1968 Filed Sept. 10, 1965 INVENTOR. SIEGFRIEDSCHMIDT AGEN F lG.2

1968 s. SCHMIDT I 3,419,752

MULTIPLE SPARK PRINTER Filed Sept. 10, 1965 Sheet 3 of 3 -153 INVENTORSIEGFRIED SCHMIDT United States Patent 3,419,752 MULTIPLE SPARK PRINTERSiegfried Schmidt, Hamburg, Germany, assignor to North American PhilipsCompany, Inc., New York, N.Y., a corporation of Delaware Filed Sept. 10,1965, Ser. No. 486,448 Claims priority, applicatig sl figrmany, Sept.11, 1964,

i 7 Claims. (Cl. 315-35) In high speed printers and tape-punchingmachines utilizing electric spark generated shockwaves the individualspark gaps have to be arranged close to one another. In such atape-punching machine one spark gap is re quired for each of the usuallyfive to eight parallel code hole tracks. The spacing between the saidtracks is usually approximately 2.5 mm. and the spark gaps musttherefore also be spaced apart the same distance. In a highspeed printerutilizing spark generated shoc-k waves one spark gap is provided foreach character printing area of a line. In this machine the spacingbetween the spark gaps is equal to the width of a character printingarea, for example, from 2.5 mm. to 4 mm. To obtain a service able outputthe inductance in a spark discharge circuit must be as low as possible.Thus two important requirements are imposed upon such a group of sparkgaps: small distance between the gaps and low inductances of the supplyconductors. A further requirement is that the heat produced can bedissipated satisfactorily.

An object of the invention is to provide a device having a group ofspark gaps which fulfills the above requirements due to the completedischarge circuit comprising the spark gaps, the discharge capacitorsand the supply leads forming a unit.

It is known to build together a spark gap, discharge capacitor andsupply conductors for producing electric sparks for lighting purposes.This known, however, comprises only a single spark gap of coaxial form.Such a coaxial form is unsuitable, however, for arranging a plurality ofspark gaps close to one another since, with the comparatively smalldiameters than to be utilized, the necessary capacitance requires agreat length of the coaxial capacitor (cylindrical capacitor).Furthermore an aperture must be provided through which the pressure wave'which is building up cylindrically about the axis of the spark impingessubstantially directly on the object (paper and matrice or character).This is difficult to realise with a coaxial form of the spark gap.

According to the invention in a device having closely adjacent sparkgaps constituted by spark electrodes and separate igniting electrodes bythe use of a block consisting of alternately dielectric layers and metallayers, the individual metal layers in each case constitutingalternately the supply conductor to one spar-k electrode, which alsoserves as a capacitor electrode, and a further capacitor electrode Whichis directly connected to the other spark electrode of the spark gap.

In stacking, the sequence of the layers and plates is thus as follows:supply conductor to one electrode, insulation, supply conductor to theother electrode, insulation, etc. Preferably, the dielectric materialused for the required insulating plates is such that the capacitancebridging a spark gap suffices for the capacitor to act as a supplycapacitor for the electric spark. These capacitors, referred to asdischarge capacitors, are comparatively cheap to manufacture for theenvisaged purpose.

In order that the invention may be readily carried into effect, twoembodiments thereof will now be described in detail, by way of example,with reference to the accompanying drawings.

FIG 1 is a perspective view of one embodiment of a 3,419,752 PatentedDec. 31, 1968 multi-electric spark discharge block of a high speedprinter according to the invention.

FIG. 2 is a diagrammatic view of the circuit of the discharge blockaccording to the invention.

FIG. 3 is another perspective view of a different embodiment of adischarge block according to the invention.

An assembly according to the invention comprises a plurality of sparkgaps including electrodes, supply conductors and capacitors, whichassembly is referred to hereinafter as the discharge block. A simpleembodiment of a discharge block is the open structure shown in FIG. 1.In this embodiment, for example, n spark gaps (only three are shown) aredefined by each pair of spar-k electrodes A K Az-Kg, etc. to A K Eachspark gap defining a pair of electrodes having associate therewith anigniting electrode Z Z etc. to Z The electrodes A to A all of which havethe same potential, are placed in a copper block 1 which represents thepoint 0 in the circuit diagram shown in FIG. 2. The opposing sparkelectrodes K to K are soldered to copper plates 2, 2", etc., which serveas supply conductors and also as large area contacts with one of thecapacitor electrodes, C l, C l, etc., said copper plates 2 beingconnected to points 0 to c respectively in the circuit diagram of FIG.2. the electrodes A to A are arranged opposite to the electrodes K to KAn insulating strip and spacer 3 separates the copper plates 2', 2",etc., from the copper block 1 and provides the necessary and properspacing between the electrodes A and K. The igniting electrodes Z to Zare fixed in bores in the strip 3.

Between each two adjacent copper plates 2, 2", etc., connected to thespark electrodes K and K for example plates 2" and 2, there are arrangedtwo dielectric plates 4, 4' for example ceramic plates, which areseparated by a further copper plate 5. All the copper plates 5 areconnected to the copper block 1, as may be seen from the copper plates 5and 5" (which is broken away). :Each of the plates 5 forms a large areacontact with the other electrode of one of the capacitors C C to C C anda supply conductor to one of the electrodes A to A (FIG. 2).

The capacitor electrodes 5 themselves are metal layers provided in theusual manner on the dielectric plates 4, which metal layers must notextend, at least on the upper side in FIG. 1, as far as the edges of theplates 4 in order to obtain adequate insulation. To ensure good passageof the spark current it is advantageous to solder the said metal layers5 to the copper block 1. The plates 5 are made as thin as possible topermit a substantial number to be used for storage of dielectric charge.

The stack comprising the plurality of copper plates 2 and 5 and thedielectric plates 4 in each case begins and terminates with a plate 5.Thus two capacitors, each separated by a dielectric plate, are connectedin parallel with each spark gap. So the volume of two dielectric storedplates is available as the dielectric charge volume for each spark gap.

The maximum storage of electrical energy is obtained if the dielectricis charged to its maximum permissible field strength. For all thecapacitors of the discharge block the length of the spark gaps and thedistances from spark gap to spar-k gap are predetermined. Thus themaximum operating voltage and the maximum operating field strength arealso determined. The material for the dielectric plates '4 is chosen asa function of the maximum operating field strength. To obtain optimumconditions it may sometimes be useful to employ different dielectrics.With discharge blocks intended for strip-punching machines and highspeed printers the operating field strength occurring is usuallycomparatively low. Ceramic material having a high dielectric constant istherefore especially suitable for the dielectric plates.

The complete discharge block consisting of capacitors C l, C l to C n, Cn is resiliently clamped together for absorbing electrostrictivevariations in thickness of the dielectric plates which occur undercertain conditions. For this purpose, clamping bolts 7 are passedthrough the bores in terminal plates 6 and press on these terminalplates from the outside with the interposition of suitable springs (notshown). Since the location of the desired action of the gaps A, K isdetermined during punching by the position of the punching matrices andduring printing by the positions of the characters the very small shiftsof the spark gaps caused by a possible electrostriction are nottroublesome.

A second embodiment, shown in FIG. 3, is especially suitable for higherpowers. In this embodiment the complete discharge block consisting of aplurality of capacitors is incorporated in a metal holder "8 closed onall sides and filled with oil. The necessary insulating distances withrespect to the open structure FIG. 1, are thus smaller. The dissipationof heat becomes very favorable and may still be improved by providingcooling fins on the holder 8 or, more efiectively still, by circulationof the oil from holder 8 through a cooler. The embodiment shown in FIG.3 has 8 spark gaps, such as may be used, for example, for a machine forpunching code holes in tape. 'In this case the spark gaps are formed, assurface-spark gaps. A copper block 9 to which the electrodes A aresoldered constitutes part of the wall of the holder 8. An insulator 10is provided in the wall of the holder 8 also to allow the passage of theelectrodes K and the igniting electrodes Z. Material especially suitablefor the insulator is ceramic material, which can be soldered to theholder, for example of copper, in a liquid-tight manner and 'with goodthermal contact.

The circuit of the embodiment shown in FIG. 3 is the same as that shownin FIG. 2 for the discharge block of open structure shown in FIG. 1. Theconnections of the igniting electrodes Z and the connections made to theplates 2 are led to the exterior, for example, through ceramiclead-through devices 11 and 12 respectively which have been closed bysoldering. The connection 0 is the housing '8 itself. Side plates 13merely serve for mounting of the device.

What is claimed is:

1. A multiple spark printer comprising means defining a plurality ofspark gaps, each said spark gap including a pair of spark electrodes inspaced opposed relation, capacitor means coupled with each said pair ofspark electrodes; said capacitor means comprising a first capacitorelectrode sandwiched between a pair of dielectric members, said firstcapacitor electrode being connected with one said spark electrode, and asecond capacitor electrode on each said dielectric member remote fromsaid first capacitor electrode, said second capacitor elctrode beingconnected with the other of said spank electrodes, and lead-in conductormeans coupled with said capacitor electrodes.

2. A multiple spark printer according to claim 1 wherein said first andsecond capacitor electrodes comprise thin films of conductive materialattached to said dielectric members.

3. A multiple spark printer according to claim 2 wherein said capacitormeans coupled with each said pair of electrodes have differentdielectric values.

4. A multiple spark printer according to claim 2 with the addition ofmeans for resiliently clamping together said capacitor means for eachsaid spark gap.

5. A multiple spark printer according to claim 1 wherein said meansdefining a plurality of spark gaps cornprises, a bar of conductivematerial having a plurality of spark electrodes projecting therefrom inthe same direction in spaced parallel relation, said bar being connectedwith one of said first and second capacitor electrodes, and aninsulator-spacer member extending parallel with said pro jecting sparkelectrodes for separating said bar from said capacitor means and theassociated spark electrodes thereof, one said lead-in conductor meansbeing coupled with said bar.

6. A multiple spark printer according to claim 1 with the addition ofhousing means of conductive material euclosing said capacitor meanscoupled with one of said first and second capacitor electrodes.

7. A multiple spark printer according to claim 6 wherein said meansdefining a plurality of spark gaps comprises said housing means; saidhousing means having a wall member including a first plurality ofsurface electrodes integral therewith and connected through said housingmeans with one said lead-in conductor, an insulator means in said wallmember adjacent said surface electrodes, and a second plurality ofsurface electrodes in said insulator means in spaced opposed relationwith said first plurality of electrodes, and means for connecting theother of said first and second capacitor electrodes.

References Cited UNITED STATES PATENTS 1,683,590 9/1928 Atherton 313-268X 2,618,765 11/1952 Vogelsanger 313---268 X JOHN W. HUCKERT, PrimaryExaminer.

R. F. POLISSACK, Assistant Examiner.

U.S. Cl. X.R.

1. A MULTIPLE SPARK PRINTER COMPRISING MEANS DEFINING A PLURALITY OFSPARK GAPS, EACH SAID SPARK GAP INCLUDING A PAIR OF SPARK ELECTRODES INSPACED OPPOSED RELATION, CAPACITOR MEANS COUPLED WITH EACH SAID PAIR OFSPARK ELECTRODES; SAID CAPACITOR MEANS COMPRISING A FIRST CAPACITORELECTRODE SANDWICHED BETWEEN A PAIR OF DIELECTRIC MEMBERS, SAID FIRSTCAPACITOR ELECTRODE BEING CONNECTED WITH ONE SAID SPARK ELECTRODE, AND ASECOND CAPACITOR ELECTRODE ON EACH SAID DIELECTRIC MEMBER REMOTE FROMSAID FIRST CAPACITOR ELECTRODE, SAID SECOND CAPACITOR ELECTRODE BEINGCONNECTED WITH THE OTHER OF SAID SPARK ELECTRODES, AND LEAD-IN CONDUCTORMEANS COUPLED WITH SAID CAPACITOR ELECTRODES.